Landsat 7 Processing Definitions

Descriptive information pertaining to the associated data files or data products. Information includes location and spatial coverage of the digital image data, acquisition date, associated file content, and data quality. Metadata are generated for the Level 0R data files and for the Level 0R, 1R, and 1G data products.

Browse Image
Sub-sampled Level 0R digital image of the Earth that can be viewed on a scene basis to quickly assess general ground area coverage, data quality, and the spatial relationships between ground area coverage and cloud coverage. A browse image provides a coarse spatial resolution image with a reduced data volume to facilitate screening of the archived Landsat 7 data.

Calibration Parameter File
Parameters required to radiometrically and geometrically correct Level 0R digital image data to generate Level 1R or 1G data products. The parameters are based on calibration of the ETM+ and the Landsat 7 spacecraft.

Level 0R Data File
Level 0R digital image data (see description below); payload correction data from the spacecraft including attitude, ephemeris high frequency jitter data, and ETM+ and spacecraft temperatures; mirror scan correction data; a geolocation table; and internal calibration lamp data.

Level 0R Digital Image Data
Reformatted, raw data acquired by the ETM+ as it views the Earth. Reformatting for ETM+ includes: 1) reversing the order of the reverse scan data, 2) aligning the staggered detectors, 3) nominal alignment of the forward and reverse scans. The data are not radiometrically corrected, the pixels are not resampled, and the pixels are not registered to a map projection.

Level 0R Data Product
Level 0R data files packaged and formatted for distribution to Landsat 7 data users along with the associated metadata and calibration parameter file. Data products are generated on request by a data user. A user may specify a subset of a Level 0R digital image or a subset of the data files for distribution.

Level 1R Data Product
A radiometrically corrected ETM+ digital Earth image along with the files containing metadata, calibration parameters, payload correction data, mirror scan correction data, a geolocation table, and internal calibration lamp data. The digital image pixels are not resampled for geometric correction and registration. Level 1R data products are generated on request and the data are packaged and formatted for distribution to the data user.

Level 1G Data Product
A radiometrically corrected and geometrically corrected ETM+ digital Earth image along with metadata, calibration parameters, and a geolocation table. The radiometrically corrected pixels are resampled for geometric correction and registration to a user-specified map projection. Level 1G data products are generated on request and the data are packaged and formatted for distribution to the data user.


Section 105 of Public Law (P.L.)102-555, The Land Remote Sensing Policy Act of 1992, states, "The Landsat Program Management (LPM), in consultation with other appropriate United States Government agencies, shall develop a data policy for Landsat 7...". The law also identifies goals for the policy. This document, in accordance with the law, establishes a data policy for Landsat 7 that covers the acquisition, processing, archival, distribution and pricing policy for Landsat 7 data. Roles and responsibilities for Landsat 7 system development and operations are contained in the Management Plan for the Landsat Program.

As required by P.L. 102-555, this Data Policy is designed to achieve the following:

  1. Ensure that unenhanced data are available to all users at the cost of fulfilling user requests;
  2. Ensure timely and dependable delivery of unenhanced data to the full spectrum of civilian, national security, commercial, and foreign users and the National Satellite Land Remote Sensing Data Archive (NSLRSDA);
  3. Ensure that the United States retains ownership of all unenhanced data generated by Landsat 7;
  4. Support the development of the commercial market for remote sensing data;
  5. Ensure that the provision of commercial value-added services based on remote sensing data remains exclusively the function of the private sector; and
  6. To the extent possible, ensure that the data distribution system for Landsat 7 is compatible with the Earth Observing System Data and Information System (EOSDIS).

The Landsat 7 system will comprise a spacecraft carrying an Enhanced Thematic Mapper Plus (ETM+) instrument and a ground segment consisting of mission operations, data capture, ground processing, data archiving, and data product distribution elements. The ETM+ is a nadir-pointing, eight spectral band instrument designed to provide data continuity with the Thematic Mapper instruments on Landsats 4 and 5.

Data acquisition by the ETM+ on Landsat 7 will be directed by the mission goal of acquiring and updating periodically a global archive of daytime, substantially cloud-free images of land areas. In addition to the periodic global archive acquisitions, Landsat 7 will acquire every daytime scene on every pass over the United States. However, the Landsat operator will modify the acquisition schedule for the global archive mission and the standing order for scenes of the United States to accommodate time-critical observations and other requests based on the following order of priorities:

  1. Spacecraft and instrument health and safety
  2. Time critical acquisitions related to national security, natural disasters and environmental emergencies
  3. Time critical acquisitions to support large campaigns and other key US Government (USG) programs
  4. Acquisitions critical to the global archive mission
  5. Acquisition requests from individuals and commercial entities

Conflicts in the acquisition schedule will be resolved by the Landsat operator according to the priorities listed above and policy guidelines established by the Landsat Coordinating Group (LCG) acting on behalf of Landsat Program Management.

Non-time critical requests for acquisitions will be received by the EOSDIS Distributed Active Archive Center (DAAC) at the US Geological Survey's EROS Data Center (EDC) in Sioux Falls, South Dakota. Requests for time critical acquisitions will be received directly by the Landsat operator.

The primary USG ground station will be located at EDC. The ground station will have the capability to capture both real-time and recorded data via direct transmission from Landsat 7. Secondary USG ground stations for Landsat 7 will be located in the Fairbanks, Alaska area and Svalbard, Norway. The secondary station(s) will serve as backup for the primary station and ensure that the requirement for scene acquisitions is met. In addition, the Landsat 7 system will be capable of transmitting data in real-time to other, non-USG* ground stations.

USG ground stations will operate according to the data acquisition priorities defined in this document. Non-USG stations will receive data upon request and limited by the allocation of spacecraft assets for providing direct transmission data. These direct downlink resources will be scheduled in a balanced and equitable manner consistent with the achievement of the global archive mission goal.

The Landsat 7 operator will develop a standard ground station agreement which each non-USG operator must sign to be authorized to receive Landsat 7 data. This agreement will include conditions such as: provision for acquisition scheduling and availability of the direct downlink; the use of non-USG ground stations as contingency backups or supplements for USG data acquisition; retention of ownership by USG of all unenhanced data from Landsat 7; the reception, archiving and cataloging of remotely received data; the availability of these data; exchange of metadata and image data between the non-USG ground station and the EDC-DAAC; the technical services available to the ground stations; and the fees associated with access to data. The Landsat 7 operator will endeavor to provide all requested coverage with the ETM+ sensor within the coverage circle of authorized ground stations, within the limits of the Landsat 7 system's resources and in accordance with conflict resolution guidelines.

EDC will generate Level 0R data files, metadata, and browse images for all Landsat 7 data received by the Landsat 7 Ground Station at EDC. The EDC-DAAC will provide access to the Landsat 7 metadata and browse images on a non-discriminatory basis and will generate Level 0R, Level 1R, and Level 1G data products on request (see Attachment for descriptions of the data products) for distribution to Landsat data users.

Data processing beyond the Level 1 products distributed through EDC is the responsibility of the users and will be accomplished with user-owned capabilities or those available from private sector suppliers.

EDC will archive, at a minimum, all Landsat 7 Level 0R data files, metadata, and browse images generated at EDC and metadata and browse products provided to EDC by the Landsat 7 non-USG ground stations.

Landsat 7, Level 0R, Level 1R and Level 1G data products will be distributed in a timely manner on a non-discriminatory basis, within the technical limitations of the system. The USG will impose no restrictions on subsequent use, sale, or redistribution of data from Landsat 7.

Should demand for data products exceed the daily capacity at EDC, orders for data will be processed based on the same priorities as data acquisition.

EDC will provide standard services associated with distribution of Landsat 7 data including distribution in defined, standard product format(s). Data will be available on physical media and via electronic transfer.

All users will be charged standard prices for the products/services provided. Prices will be reviewed and established by LPM once per year. It is intent of LPM to distribute Level 0R data for no more than $500 per scene.

Landsat 7 and ETM+ Characteristics

Band Number Spectral Range(microns) Ground Resolution(m)
1 0.45 - 0.515 30
2 0.525 - 0.605 30
3 0.63 - 0.690 30
4 0.75 - 0.90 30
5 1.55 - 1.75 30
6 10.40 - 12.5 60
7 2.09 - 2.35 30
Pan 0.52 - 0.90 15

Swath width: 185 kilometers
Repeat coverage interval: 16 days (233 orbits)
Altitude: 705 kilometers
Quantization: Best 8 of 9 bits
On-board data storage: ~375 Gb (solid state)
Inclination: Sun-synchronous, 98.2 degrees
Equatorial crossing: Descending node; 10:00am +/- 15 min.
Launch vehicle: Delta II
Launch date: April 1999

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